There is no freighter side anymore, the two operations were merged over two years ago. There is no age limit listed on the application. Medical tests have been covered on this thread numerous times, it evolves stress test, electroencephalogram, numerous eye tests, hearing test, blood work, X-rays, sonograms....! Think NASA
I would recommend to go back a couple of years worth of information on this thread and you will find all the information you need and some you didn't think you needed.